Nowadays cans or tubes are manufactured in extremely efficient production lines and then need packing for further shipment. This is done by either placing the tubes or cans into boxes or by assembling them into larger formations which are then strapped together, whereupon these formations are placed on pallets and shipped.
To this end the applicant has developed special grouping units in which the tubes or cans continuously arriving from a production line are arranged in groups of adjacent tubes or cans with a specifiable unit number, whereupon these groups are each handed over to a transport unit. This transport is often a pusher which pushes these cans or tubes into a carton, layer by layer.
Furthermore for intermediate transport the applicant has also developed an auxiliary form, usually in the shape of a hexagon, into which the grouped tubes or cans are pushed layer by layer to be then transported further to a strapping station. Such a solution is shown in the DE 1 0006 484 A.
The market also offers packaging plants, in which tubes or cans are picked up group-wise by means of a handling robot so that a formation is formed which is then strapped.
Furthermore the applicant has developed a method and an apparatus for packing tubes or cans, where the cans or tubes are pushed by the grouping unit onto a plate with a plurality of spikes arranged tightly together, until a desired formation is formed, whereupon this spike plate conveys this formation of tubes and cans further in order for them to be packed into boxes. In order to be able to achieve the required output, such a plant nowadays preferably comprises two such spike plates which in turn interact with the grouping unit.
Although such a packaging plant admittedly operates at high speed, these days production lines are operated at constantly increasing speeds, and the known plant according to European Patent EP 1 656 298 has reached its limit of performance.
In order to increase its performance, it would be possible to increase the strapping speed thereby gaining a few tenths of a second, but as the strapping speed increases, so does the pulse with which the plastic strap is whipped around the formation thereby often causing damage to the tubes or cans in the outer circumferential regions. One of the reasons for this is that the tubes as well as the cans are manufactured with an ever decreasing wall thickness.
During strapping the formation of tubes or cans must remain fixed in its position, and therefore the spike plate or the handling robot cannot let go of the formation and return to the grouping unit until strapping of the formation of cans or tubes has been completed.